Objective: Survivin is one of the apoptosis inhibitor proteins and is rarely expressed in adult normal tissues. However, survivin expression has been detected in various tumors. In this study, we evaluated the usefulness of urinary survivin/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) ratio as a marker for bladder tumor.
Patients and methods: Urine samples were obtained from 72 patients with bladder tumor, 36 with urinary tract inflammation as controls. Survivin and GAPDH mRNA expression was measured by quantitative real-time PCR assay in urine cells. The GAPDH housekeeping gene was used for normalization of survivin expression. We also analyzed survivin protein levels using urine samples and recombinant protein by western blotting.
Results: High expression of survivin was confirmed on the protein level using urine samples of bladder tumor by western blotting. Survivin/GAPDH mRNA ratios of bladder tumor quantified by real-time PCR was significantly higher than those of controls (p=0.001). In pathological stage of bladder tumor, survivin/ GAPDH mRNA ratio of pTis was significantly high compared with pTa and pT1 (p < 0.001, p=0.001, respectively). Grade3 tumors expressed high level of survivin/GAPDH mRNA ratio compared with Grade 1 and Grade 2 tumors (p=0.03). The sensitivity, the specificity and AUC(area under the curve) of survivin/ GAPDH mRNA ratio was 83.3%, 86.1% and 0.898, respectively.
Conclusion: Measuring survivin/GAPDH mRNA ratio in urine is non-invasive and high sensitive examination. Therefore, survivin/GAPDH mRNA ratio is useful marker for the detection of bladder tumor, especially to detect carcinoma in situ.